An estimation model for electromechanical property coefficients (electromechanical coupling coefficient, piezoelectric constant, dielectric constant, elastic compliance) is proposed to estimate quantitatively the property - microstructure relations of ceramics. These relations facilitate design of the microstructure of ceramics with desirable energy transformation. This model, which is a modification of the previous model for the dielectric constant of barium titanate ceramics, allows quantitative evaluation of ehe effects on electromechanical property coefficients of the size or thickness distribution of grain, pore and grain boundary in real ceramics. It is confirmed that the simulation results using the proposed model agreed well with the experimental ones, which are sensitive to changes in operating conditions. And by analysis of the dependence of microstructure on electromechanical property coefficients which are simulated in detail, it is possible to design a microstructure with desirable properties. Additionally, this method is useful to estimate the electrical properties of piezoelectric composite materials.